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PLoS Negl Trop Dis. 2017 Nov 27;11(11):e0006103. doi: 10.1371/journal.pntd.0006103. eCollection 2017 Nov.

The importance of thinking beyond the water-supply in cholera epidemics: A historical urban case-study.

Author information

1
Copenhagen Center for Disaster Research (COPE), Department of Public Health, Faculty of Health and Medical Sciences, Copenhagen, Denmark.
2
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
3
Center for Communicable Disease Dynamics, Harvard TH Chan School of Public Health, Boston, MA, United States of America.
4
Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America.
5
Department of Science and the Environment, Roskilde University, Roskilde, Denmark.

Abstract

BACKGROUND:

Planning interventions to respond to cholera epidemics requires an understanding of the major transmission routes. Interrupting short-cycle (household, foodborne) transmission may require different approaches as compared long-cycle (environmentally-mediated/waterborne) transmission. However, differentiating the relative contribution of short- and long-cycle routes has remained difficult, and most cholera outbreak control efforts focus on interrupting long-cycle transmission. Here we use high-resolution epidemiological and municipal infrastructure data from a cholera outbreak in 1853 Copenhagen to explore the relative contribution of short- and long-cycle transmission routes during a major urban epidemic.

METHODOLOGY/PRINCIPAL FINDINGS:

We fit a spatially explicit time-series meta-population model to 6,552 physician-reported cholera cases from Copenhagen in 1853. We estimated the contribution of long-cycle waterborne transmission between neighborhoods using historical municipal water infrastructure data, fitting the force of infection from hydraulic flow, then comparing model performance. We found the epidemic was characterized by considerable transmission heterogeneity. Some neighborhoods acted as localized transmission hotspots, while other neighborhoods were less affected or important in driving the epidemic. We found little evidence to support long-cycle transmission between hydrologically-connected neighborhoods. Collectively, these findings suggest short-cycle transmission was significant.

CONCLUSIONS/SIGNIFICANCE:

Spatially targeted cholera interventions, such as reactive vaccination or sanitation/hygiene campaigns in hotspot neighborhoods, would likely have been more effective in this epidemic than control measures aimed at interrupting long-cycle transmission, such as improving municipal water quality. We recommend public health planners consider programs aimed at interrupting short-cycle transmission as essential tools in the cholera control arsenal.

PMID:
29176791
PMCID:
PMC5720805
DOI:
10.1371/journal.pntd.0006103
[Indexed for MEDLINE]
Free PMC Article

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